This invention relates to a reversible ratchet wrench with a control switch that is subject to be controlled by the thumb or other fingers of the hand grasping the ratchet wrench.
The reversible ratchet wrench is a popular mechanical tool used to tighten or loosen threaded elements, e.g. nuts and bolts. The reversible ratchet wrench converts a continuous rocking movement into an intermittent rotational movement. Therefore, the time required to tighten or loosen the threaded elements is shortened and its operations are also simplified. However, conventional reversible ratchet wrenches still have a few drawbacks which will be described in detail hereinafter. Two conventional reversible ratchet wrenches, 100 and 110, with corresponding control switches, 105 and 115, are shown in FIG. 5 and 6, respectively. In both above-referenced conventional ratchet wrenches 100 and 110, the control switches 105 and 115, which change the driving directions of the ratchet wrenches, are disposed at (or near) the head portion thereof. The control switches of conventional ratchet wrenches, such as shown in FIG. 5 and 6, are not accessible to the same hand that grasps the ratchet wrench. Hence, it would be necessary to first detach the wrench from the tool intended to be driven and then to turn the control switch with another hand when the driving direction of the ratchet wrench is to be changed. This would therefore cause the operation to be inconvenient. In addition, when a bolt or a nut has been attached to the threaded hole but is still in a loose-connection situation, the reverse (non-driving) rotation would cause the bolt or nut to move in the reverse direction due to the significant friction between the ratchet wheel and the pawl. Therefore, it is usually necessary to rotate the bolt or nut to a semi-tightened situation by hand and then to further tighten it by the ratchet wrench. This would be the same condition as that when the bolt or nut has been loosened to a loose-connection situation, in which it would be necessary to further loosen the bolt or nut by hand. Conventional reversible ratchet wrenches therefore still waste time and involve a complicated procedure as described in the above-described operation.